1. Field of the Invention
This invention relates to data recording and/or reproducing apparatuses and, more particularly, to a method for identifying a type of a disc mounted in a data recording and/or reproducing apparatus.
2. Description of Related Art
All types of data discs, such as compact discs (CDs), video compact discs (VCDs), and digital versatile discs (DVDs), are widely used as storage media for storing vast information. Related data recording and/or reproducing apparatuses are also developed for recording data onto and/or reproducing data from the discs. Generally, a disc includes a read-out surface and a recording layer where a plurality of recording tracks are formed. A data recording and/or reproducing apparatus emits a light beam that is projected on the read-out surface and then reaches the recording layer to record data onto or reproduce data from the disc.
With rapid developments of the data recording and/or reproducing apparatuses, many recording and/or reproducing apparatuses are now required to be operable with as many types of discs as possible. However, different discs may have different inherent formats, such as distances from the read-out surfaces to the recording layers, radial distances between two adjacent tracks (so called track pitch). For example, a distance from the read-out surface to the recording layer of a CD is greater than that of a DVD. In order to properly record data onto or reproduce data from a disc, a wavelength and a power of the light beam should be adjusted according to the type of the disc. Thus, when the disc is mounted in the data recording and/or reproducing apparatus, the first thing the data recording and/or reproducing apparatus does is to identify the type of the disc.
A conventional method for identifying whether a disc is the CD or the DVD is implemented by irradiating light beams with two different wavelengths onto the disc. Because the CD and the DVD have different distances from the read-out surfaces to the recording layers, light beams reflected from the CD and the DVD are different from each other, thereby being capable of discriminating the CD from the DVD.
Following developments of storage technologies, more and more discs such as forward versatile discs (FVDs), and high-density DVDs (HD-DVDs), with small track pitches are introduced. However, the conventional method cannot identify discs that have same distances from the read-out surface to the recording layer but have different track pitches. For example, referring to FIG. 5 and FIG. 6, a track pitch of a DVD is 0.74 μm, while a track pitch of an FVD is 0.64 μm.
Therefore, a method for identifying a type of a disc that can discriminate discs with different track pitches is desired.